Method of producing epitactic semiconductor layers on foreign substrates

ABSTRACT

A method of producing thin, monocrystalline layers of semiconductor material, upon a monocrystalline, preferably wafershaped, substrate body of another chemical composition, but having the same or a similar lattice structure, by an epitactic growth process. The substrate body is immersed into a melt comprising the appropriate semiconductor material. A temperature balance between the substrate body and the melt, is established. Thereafter the semiconductor material epitactically grown on the surface of the substrate body, by slowly pulling the substrate body out from the melt.

United States Patent Grabmaier Mar. 21, 1972 [54] METHOD or PRODUCING EPITACTIC Lsgl ReterelLes tilted SEMICONDUCTOR LAYERS ON UNITED STATES PATENTS FOREIGN SUBSTRATES 3,341,361 9/1967 Gorski ...1 17/120 [72] Inventor: Josef Grabmaier, Unterhaching, Germany 3 411 94 11 19 3 T a 1 17 20 [73] Assign: Siemens Aktiengmuschafi Berlin" Gap 3,414,434 12/1968 I Manasevrt ..117/201 many Primary ExaminerWilliam P. Jarvis [22] Filed: Sept. 25, 1969 Anomey-Curt M. Avery, Arthur E. Wilfond, Herbert L.

Lerner and Daniel J. Tick [21] Appl. No.: 860,942

' [57] ABSTRACT [30] Foreign Application Priority Data A method of producing thin, monocrystalline layers of semiconductor material, upon a monocrystalline, preferably Sept. 30, 1968 Germany ..P 17 94 273.3 wafebshaped, substrate y of another chemical composi tion, but having the same or a similar lattice structure, by an [52] US. Cl ..117/201, 117/120, 23/301 SP epitacfic growth procem The substrate body is immersed into [51] 3'- 1/18, 0117/40 a melt comprising the appropriate semiconductor material. A Fleld Of Search ..1 A; temperature balance between the substrate and the melt is established. Thereafter the semiconductor material epitactically grown on the surface of the substrate body, by slowly pulling the substrate body out from the melt.

2-- i 3 k ewinsfis r s METHOD OF PRODUCING EPITACTIC SEMICONDUCTOR LAYERS ON FOREIGN SUBSTRATES My invention relates to a method to produce epitaxially thin, monocrystalline layers comprised of semiconductor material, upon a monocrystalline, preferably wafer-shaped, substrate body comprised of another chemical composition but having the same or similar lattice structure.

When integrated semiconductor circuits are produced on a foreign substrate material, it is desirable to precipitate, the thinnest possible layers of semiconductor material upon a foreign substrate with high crystal perfection. This is done to prevent the following:

1. Crystal errors of the substrate do not migrate into the grown layer which layer is responsible for the function of the integrated semiconductor circuit;

2. Precipitations in the substrate, which can occur, when heat treatments in the substrate at the temperature range of precipitation should not produce growth disturbances in the growing layer;

3. Outside or apparatus influences should not cause disturbances in form of contaminating particles in the layer;

4. Lattice deviations of the growth layer from the lattice of the substrate, should not produce errors in the growth layer.

The method of the invention eliminates the aforedescribed disadvantages by immersing the substrate body into a melt, comprised of the respective semiconductor material. An epitactic growth of semiconductor material be effected on the surface of the substrate body by establishing a temperature balance between the substrate body and the melt and thereafter slowly pulling the substrate body out from the melt.

It is within the scope of the invention to use a pulling velocity of 50 to 100 mm./hr. for pulling the substrate body, coated with the semiconductor layer.

According to a particularly preferred embodiment of the teaching according to my invention, a substrate body is employed which possesses properties of electrical insulation, and, preferably, a spinel structure. Very satisfactory results were obtained when a Mg-Al spinel crystal, is used as a substrate, having a composition of MgO:Al O as 1:] to 123.5, and preferably 1:1 to 1:25 It is preferable that the substrate surface, intended for coating, have a 100) plane orientation.

According to another embodiment of the invention, when sapphire (or corrundum) are employed as substrate bodies, the substrate surface selected for coating, is oriented in the (001) plane.

Silicon, germanium or A'"B" compounds, particularly gallium arsenide, can be deposited as semiconductor materials.

To produce semiconductor layers of variable conductance type and/or variable conductivity, dopant substances are being added to the melt.

It is in the scope of the invention to precipitate a plurality of semiconductor layers of variable conductivity, from the same or from a different semiconductor material, in an appropriate sequence. The substrate body that is coated with the last applied epitactic layer, is used as the original substrate body for the next epitactic precipitation of semiconductor material.

The method of the invention affords the possibility to produce thin-layer semiconductor components on foreign substances and, if necessary, to form the same from multiple monocrystalline layers.

The invention will be more fully described with respect to the drawing in which:

FIG. 1 shows the body produced by the invention; and

FIG. 2 schematically illustrates the producing of the body.

FIG. 1 illustrates a simple layer sequence, which occurs by the invention, the monocyrstalline substrate body 1, is a Mg- Al spinel, preferably wafer-shaped, of the following composition: MgO:Al O; '-1:2.5. A silicon layer 2, approximately 1011. thick, is deposited by epitactic precipitation upon the substrate body. The silicon layer which occurs, of necessity, on the bottom side of the substrate body is removed by mechanical means, or through etching. The, thus obtained, spinel crystal provided with the semiconductor layer, IS being further processed according to known methods of the planar technique, into integrated semiconductor circuits, having an insulated foreign substrate.

FIG. 2 schematically illustrates a device for performing the method of the invention. 3 indicates the semiconductor metal, located in a crucible 4. A semiconductor layer 2 is epitactically produced on the surfaces oriented in a plane by pulling, from said semiconductor melt at a velocity of 50 mm./hr., in the direction of arrow 5, a monocrystalline Mg-Al spinel crystal 1 as a seed.

1 claim:

1. A method of producing thin, monocrystalline layers of semiconductor material, upon a monocrystalline, preferably wafer-shaped substrate body of another chemical composition, but having the same or a similar lattice structure, by employing an epitactic growth process, which comprises immersing a substrate which has electrically insulating properties and a spinel structure into a melt comprising the appropriate semiconductor material establishing a temperature balance between the substrate body and the melt, and thereafter slowing pulling the substrate body from the melt at a velocity of 50 to 100 mm./hr. to effect an epitactic growth of semiconductor material on the surface of the substrate body.

2. The method of claim 1, wherein the substrate is a Mg-A| spinel of the composition: MgO:Al O =l:l to 1:35

3. The method of claim 1, wherein the substrate is sapphire or corrundum, and is oriented in the (001) plane.

4. The method of claim 1, wherein the melt is a silicon melt.

5. The method of claim 1, wherein the melt is a germanium melt.

6. The method of claim 1, wherein the melt is an A'"B" compound.

7. The method of claim 6, wherein the melt is gallium arsenide.

8. The method of claim 1, wherein dopant substances are added to the semiconductor melt.

9. The method of claim 1, wherein several semiconductor layers of variable conductivity and comprised of the same or of different semiconductor material, are sequentially applied, upon the substrate body, and the substrate body, which was last coated with the layer serves as the substrate body for the next epitactic precipitation. 

2. The method of claim 1, wherein the substrate is a Mg-Al spinel of the composition: MgO:Al2O3 1:1 to 1:3.5.
 3. The method of claim 1, wherein the substrate is sapphire or corrundum, and is oriented in the (001) plane.
 4. The method of claim 1, wherein the melt is a silicon melt.
 5. The method of claim 1, wherein the melt is a germanium melt.
 6. The method of claim 1, wherein the melt is an AIIIBV compound.
 7. The method of claim 6, wherein the melt is gallium arsenide.
 8. The method of claim 1, wherein dopant substances are added to the semiconductor melt.
 9. The method of claim 1, wherein several semiconductor layers of variable conductivity and comprised of the same or of different semiconductor material, are sequentially applied, upon the substrate body, and the substrate body, which was last coated with the layer serves as the substrate body for the next epitactic precipitation. 